PROJECT SUMMARY Multiple sclerosis (MS) is an autoimmune disease in which myelin lining the central nervous system is attacked, leading to a debilitating loss of motor function in the more than 2.5M people with MS. Effective drugs are available to help slow MS, but many of these are injectable formulations that patients can no longer self-administer as they lose dexterity and coordination during disease progression. Further, because MS patients require a large number of injections over decades, patients experience a high incidence of injection-related adverse events. Clinical studies reveal these challenges significantly decrease quality of life and patient compliance, ultimately reducing the efficacy of MS therapies. During this Bioengineering Research Grant (BRG) we will combine engineering expertise, degradable microneedle (MN) patches, and approved human MS drugs to build the first MN patches for treating MS or tolerance. We will synthesize MNs from glatiramer acetate (GA), one of the most widely-prescribed MS drugs. GA is comprised of a mixture of myelin peptides. Despite wide-spread usage, however, the functional mechanism of GA is unclear. The myelin-derived composition of GA, along with new studies revealing GA functions at least in part by directing immune response to myelin away from inflammation, provide clues there may be a component of myelin-specific tolerance. Across three aims, we will 1) characterize the physiochemical properties or MNs loaded with GA and the states these cargos are released in, as well as the in vitro interactions with myelin-reactive cells, 2) assess biodistribution and MN-induced tolerance in skin, lymph nodes, and spleen, and 3) show MNs are efficient and efficacious in two mouse models of MS (EAE, RR- EAE). Importantly, all of our studies ? from structural comparisons to disease efficacy ? will be benchmarked against the current injectable GA form and regimen used clinically. Our plans are supported by strong initial data confirming MNs can be designed with GA, and that during EAE and RR-EAE, MNs reduce T cell infiltration to the CNS and are efficacious, even at doses where GA administered by traditional injections in ineffective. Thus, GA-MNs could improve compliance and efficacy by efficiently targeting specialized skin-resident immune cells, while also creating the possibility of significant dose sparing. Throughout the aims, we will use an iterative feedback and design strategy by which the 1st Generation MNs we develop are improved to 2nd Generation MNs. These prototypes will integrate tunable release technology to further improve patient compliance, and increase robustness by extension to other classes of MS drugs. Our work is facilitated by our established multidisciplinary team that includes bioengineers, immunologists, and MS-focused clinicians. Further, the team has a history of productive collaboration on projects focused on immune tolerance. With support from the BRG mechanism, by the end of this proposal we will have strong positioning to push the work toward the hands of MS patients, an advance that could have a real impact on patient quality, compliance, and drug efficacy.